I have not done an Omni D, but all Ten Tec PTO’s are essentially the same. I’ve
done a few Century 21’s, Triton’s etc.
The PTO’s are generally pretty easy to get out of the radio and this task does
not require much guidance.
If you have some patience, I have a Century 21 that needs this work and I might
be able to do a video.
Most important, however, once you get the PTO out of the radio, is to work
over a large closed container to catch any parts that unexpectedly fall off the
assembly when you loosen things (happens 100% of the time).
After you loosen the screws that hold the black plastic part of the vernier in
place on the Aluminum PTO housing, you will likely find that everything is
pretty well seized due to the hardened lubricant.
To loosen everything up, gently heat with a hair dryer (not a heat gun as this
is too hot). The heat will soften the grease and will allow you to disassemble
the vernier assembly to clean it. Don’t force anything as you will most
certainly break the brass shaft, which is quit thin at the V groove where the
ball bearings run.
The lead screw of the PTO drive, which works with the knob shaft to produce the
reduction drive, has the large white piece riding on it. This is actually the
holder for the ferrite toroids that make up the permeability tuning slug.
Around this rests of coil, which should be unsoldered from the leads going to
the PC board for ease in repairing the moving parts.
On this same lead screw are a few other important pieces that serve to maintain
a zero lash operation of the lead screw. Make a drawing of how they came out
because the reinstallation is not really all that intuitive. A digital closeup
photo of the assembly before disassembly can be quite helpful This is a method
I use with most mechanical assemblies I repair and really helps as a reality
check when reassembling. Make certain you LOOK AT the photos on your PC before
you do the disassembly so you know that the photo is good enough to be of use.
The brass center shaft can possibly be worn to the point where the repaired PTO
might not work the you reassemble it. That is why the Ten Tec kits came with a
replacement shaft. If this is the case, you may be out of luck.
On the last one I did, I put the worn shaft into my lathe and cut a new “V”
groove into the knob end of the shaft at the same distance from the knob end as
was the original from the other end. Then I put the shaft in backwards with the
newly cut V groove on the bearings and I used the worn end for the knob. This
worked really well, but, of course, you need a lathe… For those adventurous
enough to try this method, I offer that, should you break the shaft while
trying to repair it, the shaft is exactly the same diameter as the inner shaft
of common dual potentiometers so you can cut a new shaft from one of those if
you have one. I have dozens… Hobby shops also have this brass stock.
Reassembly is impossible without first applying the replacement lubricant as
everything will just fall out on the floor without the grease to hold the
pieces in place. I use either Phil Woods bicycle grease or a high temperature
bearing grease for this task.
I hope this little meandering description, done from memory, was of help to
you. I don’t have one in front of me right now…
73,
Gary
W0DVN
> On Jun 10, 2016, at 11:46 PM, k7mks@comcast.net wrote:
>
> I'd appreciate comments, from those who have "been there," on the removal,
> cleaning, lubricating, and reinstalling of the PTO unit in the Omni D. The
> manual seems a little thin on this subject. There may be others, beside
> myself, who will benefit from your wisdom.
>
> Thank you joe k7mks
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